1. Field of the Invention
The present invention relates to a golf ball having a coating layer (a layer formed by coating) at its surface portion, which allows design values to be reliably reproduced, which allows dimples to be precisely shaped and sharp edged, and which can be given sufficient durability and functions to improve spin properties and travel properties, and to a production process thereof.
2. Related Art
Multipiece golf balls, such as two-piece golf balls, three-piece golf balls, etc., and thread-wound golf balls are usually produced by a process which comprises enclosing a solid core or a thread-wound core with a cover material and forming dimples by compression or injection molding, applying a coating layer on the surface of the cover material, conducting mark stamping by a transfer printing method, and then forming an outermost layer coating of the ball. In some cases, the mark stamp may be directly applied to the cover material surface, and then an outermost layer coating may be formed. One-piece golf balls are produced by a process which comprises preparing a solid core having dimples by compression or injection molding, and then subjecting the solid core to mark stamping and application of an outermost layer coating of the ball in this order In
In this case, the coating layer on the surface of the cover material and the outermost layer coating of the ball use a thermosetting coating material or a two-pack system coating material. Since coatings formed of these coating materials cannot be easily deformed by application of heat and pressure, dimples cannot be easily formed after formation of such coatings. Therefore, coating is performed after dimples are formed.
However, the above-described conventional coating formed on the cover material or outermost layer coating of a ball is formed to protect the golf ball from dirt or scratch and to improve the appearance thereof. No attempts have been made to give these coatings functions to improve spin properties and travel properties.
By contrast, the present inventors approached an idea to give a coating layer at a ball surface portion functions to improve spin properties and travel properties. In order to give the coating layer such functions, the coating layer must accordingly be made thicker. At the same time, the coating layer must have sufficient durability to maintain the functions.
However, when coating is performed after formation of dimples as conventionally practiced, the coating shallows the dimples and dulls dimple edges if formed relatively thick on dimples. This impairs preciseness of a dimple shape. Accordingly, coating thickness must be made as thin as possible in order to prevent the coating from impairing preciseness of the dimple shape. Thus, it is difficult for a coating to have a thickness such as to have sufficient durability and functions to improve spin properties and travel properties.